Process for treating petroleum emulsions



Patented May 20, 1952 PROCESS FOR TREAT 11 2c PETROLEUM EMULSIO S Raymond W. Todd and Fritz E. Fuchs, Houston, Tex., assignors to Aquaness Corporation, Houston, Tex., a corporation of Texas No Drawing. Application March 19, 1951, Serial No. 216,474

11 Claims. (01. 252-342) This invention relates to the treatment of emulsions of mineral oil and water, particularly water-in-oil petroleum emulsions, for the purpose of separating the oil from the water.

An object of this invention is to provide an improved process for breaking or separating petroleum emulsions by subjecting such emulsions to the action of a novel demulsifying composition to be described in greater detail hereinafter.

Another object is the provision of a novel demulsifier composition which is highly effective for breaking or separating petroleum emulsions.

The new demulsifier in accordance with this invention comprises a class of esterification products obtained by the reaction of a fatty acid with a particular type of hydroxylated compound.

The hydroxylated compounds employed as the intermediates in forming the final esterification product are of a specific character obtained by the reaction of an alkyl polyhydroxy compound initially containing three or more free hydroxyl groups with an oxyalkylating material consisting essentially of mixtures of ethylene oxide and propylene oxide in particular proportions.

The aklyl polyhydroxy compounds which are particularly adapted for preparation of the intermediate materials employed in making the final demulsifier composition are best exemplified by the class consisting of glycerol, polyglycerol, pentaerythritol, sorbitol, mannitol and the like. Polyglycerol is a polymer of glycerol, having in its simplest form, four free hydroxyl groups and a single ether linkage connecting two glyceryl residues as may be illustrated by the following formula:

Home omoH liquids completely soluble in water in all pro portions.

The fatty acids employed in making the final ester product may be any of the well known long chain, soap-forming fatty acids having 8 to 18 carbon atoms in the chain, such as stearic, oleic, ricinoleic, soya bean fatty acids, tall oil, linseed oil fatty acids, cocoa-nut fatty acids, and the like. The molal proportion of fatty acid to the oxyalkylated intermediate compounds may be varied to form either partial esters or fully esterified compounds or mixtures thereof. The mono-, dior tri-ester compounds appear generally to be the more effective compounds. The final ester compounds are all clear, moderately viscous liquids which are completely soluble or miscible with water in all proportions.

The procedure for oxyalkylating the polyhydroxy compounds is generally in accordance with well known procedures except that in every case the ethylene and propylene oxides are intermixed and reacted in mixed condition with the polyhydroxy material.

The resulting oxyalkylated polyhydroxy intermediates are then reacted in appropriate proportions with the selected fatty acid to. produce the desired ester products. This esterifying reaction is conducted in accordance with well known procedures for efiecting esterification between a hydroxy compound and an acid.

Following are several examples of the method of manufacture of the oxyalkylated polyhydroxy intermediate compounds and the final ester compounds employed in the process in accordance with the present invention:

OXYALKYLATED POLYHYDROXY INTERMEDIATE Example 1 46 pounds /2 mol) of glycerol, to which may be added about 4 pounds of sodium methylate as a catalyst, are placed in a Water-jacketed pressure chamber and heated to about 250 F. The chamber is purged with natural gas or methane and an atmosphere of such gas at a pressure of about 50 pounds per square inch is maintained in the chamber. 1250 pounds of ethylene oxide and 1250 pounds of propylene oxide are then pumped into the chamber, the oxides being intermixed as they are fed into the chamber. The oxides react with the glycerol and the resulting reaction tends to raise the temperature and pressure sharply. External heating is cut off and by circulation of cooling water the temperature is maintained within a range of from about 270 to about 350 F. The pressure is held to a range of from about to pounds per 3 square inch. As the reaction proceeds and the oxides are used up, the pressure drops to about that of the blanketing gas, about 50 pounds per square inch, when the reaction is completed. About 3 to 4 hours is required to complete the reaction.

The proportions of materials used in-this' example will produce an oxyalkylated product having an average molecular weight of about 5000 and this product is a light colored, relatively lowviscosity liquid which is completely soluble-in cold water.

Example 2 About 187 pounds each of ethylene and'propylene oxides are used instead of 1250 pounds each as in Example 1, and will produce an oxyalkylated glycerol product having a molecular weight of about 7500.

Example 3 About 625 pounds each of ethylene and propylene oxides are used instead of the amounts'stated in the previous examples to produce an 'oxyalkylated product having a molecular weight of about 2500.

Example 4 83 pounds of polyglycerol are substitutedfor the 46 pounds of glycerol in each of Examples 1, 2 and 3, above.

FINAL ESTER PRODUCT Example 1 Example 2 7500 pounds and 2500 pounds, respectively,of the Oxyalkylated Polyhydroxy Intermediates, Example 1 and Example 2, are substituted forthe 5000 pounds of Oxyalkylated Polyhydroxy Intel?- mediate, Example 1 in Final 'Ester Product, Example 1 above, to produce the corresponding mono-esters.

Example 3 564 pounds 2 mols) of oleic acid issubstituted for the 282 pounds in Final Ester Products, Examples l and 2, above, to produce the corresponding di-esters.

Example '4 350 pounds of tall oil are used in place of the 282 pounds of oleic acid in each or the Final-Ester Products, Examples 1 and 2 above,to produce the corresponding tall oil esters.

Example 5 700 pounds of tall oil are substituted in each case for the 564 pounds of oleic acid in Example 3 above.

Example 6 Molecular equivalents of cocoanut fatty acids.

soya bean fatty acids, stearic acid, or ricinoleic acid may be substituted for theoleic acid'an'dtall oil in each of the Final Ester ProductsfExa'mples 1, 2, 3, 4 and 5 above.

From the foregoing it will be understood that the demulsifier compositions employed in accordance with the present invention are fatty acid esters of a specific class of oxyalkylated polyhydroxy compounds, namely, aliphatic polyhydroxy compounds initially'having three0r more free hydroxyl groups whichhave been oxyalkylated with mixtures of ethylene and propylene oxides in the relative proportions stated above to produce compounds within the particular --ran'g'es of molecular weight above specified.

This specific group of compounds have been found to be exceptionally effective for breaking w-ater-in-oil petroleum emulsions.

may be brought in contactwith the emulsion to be treated in any of the numerous ways now-employed in the treatment of petroleum emulsions with chemical demulsifying agents, such, for example, as by introducing the treating agent into the well in which the emulsion-is produced, introducing the treating I agent into a conduit through which the emulsion is flowing, introducing the treating agent into a tank in which the emulsion is stored, *or introducing thetreat- 'ing agent into a container that holds a. sludge 'obtained from the bottom 'of an oil storage tank. -In some instances, it'may be advisable to introduce the treating agent into a producing-well in such a way that it will b'ecom'e'mixed with water and oil that are emerging from the surrounding strata, before said water and oil enter the barrel of the well pump or the tubing up through which said water and oil fiow to the surface of-the ground. 'After treatment the emulsion is allowed to stand in a quiescent state, usually in a settling tank, at a temperature varying from atmospheric temperatur 'to about 200 it, so as to .permit'the wateror brine to separate from the oil, it being preferable to keep the temperature low enough so as to prevent the valuable'constituents-of the oil from volatilizing. If desired, the "treated emulsion-may be acted upon biyone or the other of various kinds of apparatus now used 'in the operation of breaking petroleum emulsions, such 'as hoinogenizers, hay tanks, gun barrels, filters, centrifuges, or electrical dehydrator's.

The amount of treating agent onthe anhydrous basis that is required to break the emulsion may vary from approximately 1 part of treating agent to 500 parts of emulsion, up to a ratio of 1 part of treating agent to 20,000 parts of emulsion, depending upon the type or kind of emulsion being treated. In treating exceptionally refractory emulsions of the kind commonly'referred to as tank bottoms or residual pit oils," the minimum ratio above referred to is often necessary, but in treating fresh emulsions, i. e., emulsions that willyield readily to the action of chemical d'emulsifyin'g agents, the maximum ratioabove mentioned "will frequently produce-highly satisfactory results. For the average petroleum emulsion of-the water 'in-oil type -a ratio of l part of treatihgagen't'to 10,000 partsof emulsion will usually be found toproduce com'm'ercially satisfactory results.

Patent 1. A process for breaking petroleum emulsions of the water-in-oil type, which consists in subjecting the emulsion to the action of a demulsiiying agent consisting essentially of the fatty acid esters of an oxyalkylated polyhydroxy compound derived by the reaction of an alkyl polyhydroxy compound initially having three or more free hydroxyl groups with a mixture of ethylene and propylene oxides in which the proportion of propylene oxide is in the range of from about 15% to about 60% by weight of the mixture, and wherein the proportions of the mixed oxides to the alkyl polyhydroxy compound are such as to produce said oxyalkylated polyhydroxy compound having an average molecular weight ranging from about 2500 to about 7500, and wherein the fatty acid employed in forming said esters is a long-chain detergent forming fatty acid having 8 to 18 carbon atoms in the chain.

2. A process according to claim 1, wherein said esters are formed by reacting at least one mol of the fatty acid to each mol of said oxyalkylated polyhydroxy compound.

3. A process according to claim 1 wherein said alkyl polyhydroxy compound is a member of the class consisting of glycerol and polyglycerol.

4. A process according to claim 1 wherein said fatty acid is oleic acid.

5. A process according to claim 1 wherein said fatty acid is tall oil. Y

6. A process according to claim 1 wherein said 9. A process for breaking petroleum emulsions of the water-in-oil type, which consists in subjecting the emulsion to the action of a demulsifying agent consisting essentially of the oleic acid esters of oxyalkylated glycerol derived by reacting glycerol with a mixture of ethylene and propylene oxides in equal proportions by weight, and in an amount sufficient to produce an oxyalkylated glycerol having a molecular weight of about 5000.

10. A process according to claim 9 wherein the oleic acid esters are formed by reacting at least one mol of oleic acid to each mol of said oxyalkylated glycerol.

11. A process according to claim 9 wherein the oleic acid esters are formed by reacting two mole of oleic acid to each mol of said oxyalkylated glycerol.

RAYMOND W. TODD. FRITZ E. FUCHS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,312,732 Salathiel Mar. 12, 1943 2,454,808 Kirkpatrick -1 Nov. 30, 1948 2,500,349 De Groote Mar. 14, 1950 2,540,437 Fuchs Feb. 6, 1951 2,549,434 De Groote Apr. 17, 1951 

1. A PROCESS FOR BREAKING PETROLEUM EMULSIONS OF THE WATER-IN-OIL TYPE, WHICH CONSISTS IN SUBJECTING THE EMULSION TO THE ACTION OF A DEMULSIFYING AGENT CONSISTING ESSENTIALLY OF THE FATTY ACID ESTERS OF AN OXYALKYLATED POLYHYDROXY COMPOUND DERIVED BY THE REACTION OF AN ALKYL POLYHYDROXY COMPOUND INITIALLY HAVING THREE OR MORE FREE HYDROXYL GROUPS WITH A MIXTURE OF ETHYLENE AND PROPYLENE OXIDES IN WHICH THE PROPORTION OF PROPYLENE OXIDE IS IN THE RANGE OF FROM ABOUT 15% TO ABOUT 60% BY WEIGHT OF THE MIXTURE, AND WHEREIN THE PROPORTIONS OF THE MIXED OXIDES TO THE ALKYL POLYHYDROXY COMPOUND ARE SUCH AS TO PRODUCE SAID OXYALKYLATED POLYHYDROXY COMPOUND HAVING AN AVERAGE MOLECULAR WEIGHT RANGING FROM ABOUT 2500 TO ABOUT 7500, AND WHEREIN THE FATTY ACID EMPLOYED IN FORMING SAID ESTERS IS A LONG-CHAIN DETERGENT FORMING FATTY ACID HAVING 8 TO 18 CARBON ATOMS IN THE CHAIN. 